with IBSLQ1 do
  begin
    SQL.Text:='select blob_field from tab1 where id=1;';
    Transaction.StartTransaction;
    ExecQuery;
    FieldByName('blob_field').AsBlob.SaveToFile('image.bin');
    .....

  with IBSQL1 do
  begin
    SQL.Text:='update tab1 set blob_field=:blob_field where id=1;';
    Transaction.StartTransaction;
    ParamByName('blob_field').AsBlob.LoadFromFile('image.bin');
   .....

function TIBSQLData.GetAsBlob: IBlob;
begin
  CheckActive;
  result := FIBXSQLVAR.GetAsBlob(AsQuad,nil);
end;

b:=TIBBlobStream.Create;
    ParamByName('blob_field').AsQuad:=b;

    
b:=TIBBlobStream.Create;
b.Mode := bmWrite;
b.Database := Database1;
b.Transaction := Transaction1;
b.LoadFromFile('image.bin');
ParamByName('blob_field').AsQuad:=b.BlobID; 

function SaveToDB(AFile: String): Boolean;
const BufSize = 8 * 1024;
var
  b: TIBBlobStream;
  m: TMemoryStream;
  Buffer: array [0..BufSize-1] of char;
  BytesRead: integer;
begin
  Result := False;

  m := TMemoryStream.Create;
  m.LoadFromFile(AFile);
  m.Position:=0;

  b:=TIBBlobStream.Create;
  b.Mode := bmWrite;

  repeat
    BytesRead := m.Read(Buffer,BufSize);
    b.Write(Buffer,BytesRead);
  until BytesRead = 0;
  
  b.Finalize;

  with IBSQL1 do
  begin
    ParamByName('blob_field').AsQuad := b.BlobID;  
    ExecQuery;
    Result := RowsAffected > 0;
    Transaction.Commit;
    b.Free;
  end;
end;    

var b:TIBBlobStream;
begin
  b := TIBBlobStream.create;
 try
   b.Database := IBSQL.Database;
  b.Mode := bmWrite;
    b.LoadFromFile(...);
    IBSQL.ParamByName('blob').asBlob := b.blob;
  finally
    b.free;